This invention relates to an improved nonwoven web and the method for producing these webs. Preferably, the webs produced by the process of this invention are made of long and short fibers, i.e., textile length and paper-making fibers, with the fibers of the web being randomly oriented, the web having different concentrations of long and short fibers in different portions of its thickness.
Fibers are usually classified according to length, with relatively long or textile length fibers being longer than about one-quarter inch and generally between one-half and two and one-half inches in length. The term "long fibers," as used herein, refers to textile length fibers having a length greater than one-quarter inch and the fibers may be of natural or synthetic origin. The term "short fibers," as used herein, refers to paper-making fibers, such as wood pulp fibers or cotton linters having a length less than about one-quarter inch. While it is recognized that short fibers are usually substantially less costly than long fibers, it is also recognized in many instances that it is desirable to strengthen a short fiber product by including a blend of long fibers therein.
Nonwoven materials are structures which in general consist of an assemblage or web of fibers, joined randomly or systematically by mechanical, chemical or other means. These materials are well known in the art, having gained considerable prominence within the last 25 years or so in the consumer market, inductrial commercial market and in the hospital field. Typical of their use in hospital caps, dental bibs, eye pads, dress shields, shoe liners, shoulder pads, skirts, hand towels, handkerchiefs, tapes, bags, table napkins, curtains, draperies, etc.
Significant cost savings can be realized in a nonwoven web by using short length fibers. However, due to the low tensile strength of short length fiber webs, exclusive use of such fibers is impractical. As a result, prior art webs made from short length fibers have been commercially undesirable, not only due to their low tensile strength, but also due to the increased dusting effect caused by separation of individual fibers from the web.